Cellular immunity in Peyer's patches of rats infected with Trichinella spiralis.

A rat model of Trichinella spiralis gut infection was used to observe the sequence of developing cellular immunity in Peyer's patches and other lymphoid tissues. Whereas cellular reactivity (lymphocyte blastogenesis) for worm antigens was evident in mesenteric lymph nodes draining the gastrointestinal tract within 3 days after infection, Peyer's patch lymphocytes developed maximal reactivity 2 to 3 weeks later at the same time as the spleen and other lymphoid tissues. Furthermore, the immune reactivity found in Peyer's patches was only transient. Thus, in this parasitic gut infection, the Peyer's patch lymphoid tissue does not appear to be the first site of cellular responsiveness but rather to acquire cellular reactivity only when other lymphoid elements in the infected host have also acquired similar antigen-induced reactivity.